Process for sterilizing and preserving surgical ligatures.



CHARLES T. DAVIS, 01? BROOKLYN, NEW YORK.

EBOGESS FOR STERILIZING AND PRESERVING SURGICAL LIGATURES.

Helix-swing.

To all whom it may concern Be it known that 1, CHARLES T. DAvis, acitizen of the United States, residing at Brooklyn, in the county ofKings and State of New York, have invented certain new and usefulImprovements in Processes for Sterilizing and Preserving SurgicalLigatures, of which the following is a specification.

This invention relates to an improved process for sterilizing andstoring surgical ligatures and sutures, particularly those formed fromanimal tissue commonly known as catgut.

In the preparation tures for surgical use, of the utmost importance thatthey be absolutely sterile so as to avoid danger of infection. Severalmethods of preparing and storing the ligatures and sutures haveheretofore been tried, one of those most largely used being as follows.The catgut, after having been prepared in the usual way, is inserted ina glass tube open atone end and then dried. The tube and its contentsare then immersed in a suitable liquid, usually cumol, in a sterilizerand subjected to the necessary heat. The tubes containing the gut arenow removed from the cumol and the surplus cumol rinsed 0E of the gutwith chloroform.- After this, the tubes containing the sterile suturesare partially filled with chloroform, and the tubes are then sealed.Alcohol has also been largely used for this purpose. There are manyobjections to the use of these two latter substances, and there is alsograve objection to the present method of sterilization because itrenders possible, and in fact likely, the accidental contamination ofthe ligatures from the necessary handlings during the several-steps ofmanufacture.

It will be observed, therefore, that in the method heretofore employed,it has been necessary to use two different liquids, one, such as cumol,for sterilizing, having 'a high boiling point, and the other, such asalcohol or chloroform, for storing, being lighter and more volatile.

It is the object of the resent invention to provide a single liquicapable of performing both functions, and, moreover, being free from themany objections formerly experienced with substances employed in the oldprocesses."

Attempts to use cumol of ligatures and suas a storing fluidSpecification of Letters Patent.

it is, as is well known,

Patented J an. 111, 1916.

Application filed May 17, 1915. Serial No. 28,599.

have failed. This substance, which is one of the higher coal tarderivatives or substitution products of the benzene ring, has a boilingpoint so high that it will not readily evaporate from the ligature whenthe same is removed from the tube. Also, it has been found that thecumol which clings to the ligature proves exceedingly irritating to thewound, and its use as a tubing or storing fluid is impossible.

Chloroform has been found unsuitable as a storing fluid for manyreasons, chief among which are the following: First- Chloroform breaksdown under comparatively moderate heat into chlorin and hydrochloricacid, both of which exert an extremely harmful effect upon theligatures. Second-Under the influence of sunlight, free-chlorin,hydrocloric acid and carbonyl chlorid (phosgene) are liberated, thelatter product in particular being extremely ob jectionable. ThirdThedisagreeably irritating and harmful efiect of chloroform upon thetissues. Fourth-The inadequately low boiling point of chloroform, whichprevents the successful application of the temperature necessary for thesterilization of the tubes after being sealed. Fifth-The susceptibilityof chloroform to deterioration from age. SixthChloroform can hold waterin solution, which is very harmful to the ligatures, particularly tothat kind of ligature most widely used, namely, catgut, for as is wellknown, the slightest degree of moisture tends to convert'the collagen inthe catgut into gelatin, with the result that when the catgut issubjected to thermal sterilization it becomes brittle, weakened, andtwisted.

' Alcohol is objectionable for many reasons, chief among which are itslow boiling point, its inefficacy asa solvent of the fatty matter of theligature, and for the further reason that, as is well known, alcohol hasa strong affinity for Water, and hence it is impossible under workableconditions to secure alcohol which is perfectly free from water. abovestated, the presence of even a minute quantity of water in the storingliquid tends to convert the collagen of the gut into gelatin, with'theresult that when the gut is sub 1 jected to any adequate sterilizingtemperawhich would satisfactorily meetthe requirements of a successfulcombined sterilizing and, storing or tubing liquid. As a result of suchresearch, I have found that the lower methyl substitution products ofthe benzene ring are eminently suitable for such use. Particularly, Ihave found that the mono-methyl substitution product known as toluol ortoluene answers every requirement. Also, the di-methyl substitutionproducts known as ortho-, meta-,and paraxylene have been foundsatisfactory, as Well as mixtures of these various substances. Mixturesof any or all of these compounds with benzol itself may also beemployed.

The primary characteristics of these substances are that they areentirelynon-irritating to the tissues of the body and, while evaporatingreadily, have a boiling point sufficiently high for sterilizationpurposes.

Moreover, they do not break down or deteriorate under the influence ofheat, light,

or age, do not contain or mix with water,

and will not even hold water in suspension.

Still other valuable properties of this benzene series of hydrocarbonsare their anti septic or germicidal. virtues, their superior I heatconducting qualities, their softening and clarifying effect upon theligatures, their chemical stability, and their low cost in comparisonwith chloroform or alcohol. In addition, the products named are powerfulsolvents for oils and fats, and are therefore of great value in removingthe fats and fatty acids occurring in catgut ligatures, and which areirritating to the tissues of the bddy. As above stated, these substanceshave the characteristic of being highly volatile, which insures thatwhen the tube is broken for use by the surgeon, the substance quicklyevaporates; but if itshould happen that the ligature s applied soquickly as to prevent perfectevaporation, the substance will not haveany deleterious effect whatever upon the wound, but will simply have ashght'cooling effect, due to the evaporation.

These substances leave no residue upon evaporation, so that anypossibility of irritation of the wound from foreign bodies, (aforeign-body irritation as it is known among surgeons), is completelyavoided.

As a result of my invention, sterilization can be very effectivelycarried on after the tubes or containers are sealed, while by the ingpositive the assurance of sterility, and

coincidentally effecting a great economy in the amount of time andskilled e-flort otherwise required when conducting the processes ofsterilization and the handling of the ligatures under aseptic conditionsand amid sterile environments, as is necessary when employing the moreelaborate but less positive method heretofore in vogue, (z'. e., thesterilization of the ligatures before the sealing of the tubes and thesubsequent filling of the tubes with their contents of sterile storingfluid).

Benzol itself boils at 80.5 (1, toluol at 111, and the xylenes boil atfrom 137 to 143 C. These substitution products of the benzene ring arefor the most part obtainable by fractional distillation of coal tar, andall of them go over below or at 143 C. If distillation is carried beyondthis point, the tri-methyl derivatives, such as cumol and mesitylene,are obtained, which are of such an oily nature and are so irritating tothe tissues as to be unsuitable as a storing fluid. That portion of thedistillate approximating the constitution of the monomethyl derivativetoluene, and having a boiling point between 110 and 120 C. has beenfound to give particularly satisfactory results. Recently, other methodsof producing toluol and its homologues have been discovered. 1

With the improved storingfluid above described, the method of putting upthe ligatures is extremely simple. A ligature having been first preparedin. the usual wayis placed in a tube, and, while one end of the tuberemains open, is subjected to the necessary drying process. The tube isthen partially filled with my improved storingfluid and sealed. Thesealed tube and its contents are then subjected to a suitablesterilizing heat.

The temperature employed for steriliza- -tion varies with the nature ofthe particular liquid used, but is always substantially above theboiling point of such liquid, and in no case less than 100 C. Forexample, in using toluol, which boils at 232 F. (111 0.), a temperatureof about 240 to 250 F. would be employed, while with benzol, thetemperature would not run so high. In each instance, the temperature israised to such a point'as will produce a pressure within the tubesufficient to force the vapor well into the pores of the ligature, andthoroughly impregnate the same. No liquid more volatile than benzol canpractically be employed, since it has about as low a boiling point aswill permit the application of a sufficiently high temperature to effectsterilization without unduly raising the internal pressure in the tube.

\Vhat I claim is:

1. The process of preserving surgical ligatures and the like whichcomprises storing them in contact with a hydrocarbon having a boilingpoint between 80 and 143 C.

2. The process of preserving surgical ligatures and the like whichcomprises storing them in contact with a coal-tar distillate going overbetween 80 and 143 C.

3. The process of preserving surgical ligatures and the like whichcomprises storing them in contact with a coal-tar distillate of thebenzene series, having a boiling point at or below 143 C.

4:. The process of preserving surgical ligatures and the like whichcomprises storing them in contact with a hydrocarbon of the benzeneseries having a boiling point at or below 143 C.

5. The process of preserving surgical ligatures and the like whichcomprises storing them in contact with an organic compound containingonly hydrogen and carbon and having a boiling point at or below 143 C.

6. The process of preserving surgical ligatures and the like whichcomprises storing them in contact with the lower methyl substitutionproducts of the benzene ring.

'7. The process of preserving surgical ligatures and the like whichcomprises treating them with the methyl substitution prodnets of thebenzene ring below the trimethyl products.

8. The process of preserving surgical ligatures and the like whichcomprises treating them with methyl substitution'products of the benzenering having a boiling point at or below l i3 C.

9. The process ligatures and the like which comprises treating them withmono-methyl or di-methyl substitution products of the benzene ring, ormixtures thereof.

10. The process of preserving surgical ligatures and the like whichcomprises treating them with toluene.

In testimony whereof I have aiiixed my signature.

CHARLES T. DAVIS.

of preserving surgical

